In S.A.1695Gil-galad, the Elven King of Lindon, requested aid from Númenor when Sauron invaded Eriador. The Númenóreans sent a fleet commanded by the admiral Ciryatur, but it was delayed until 1700, by which time the beleaguered Elves were barely holding the the line of the River Lhûn. The arrival of the Númenóreans immediately changed the balance of forces such that Sauron's host was driven back with heavy casualties. Sauron suffered further defeat at Sarn Ford (on the Baranduin) and retreated to Tharbad where more of his forces joined him after coming up from the south-east.[2]

Unbeknownst to Sauron, Admiral Ciryatur had more forces at his disposal and had landed a strong force at the small Númenórean harbour at the mouth of the Gwathló River. This new contingent fell upon Sauron's rear from the south-west while Gil-galad's Elves and the other Númenóreans attacked from the north. Sauron's army was completely routed and he barely escaped himself.[2]

Sauron and his small remaining forces fled across the Isen but were caught in eastern Calenardhon. Only a small bodyguard was left when Sauron escaped to Dagorlad. Eriador had peace for many years but the humiliation inflicted on Sauron determined him to seek vengeance upon Númenor.[2]